Enhancement of p-GaN Conductivity Using PECVD SiO[sub x]

Karouta, F.; Kappers, M. J.; Krämer, Mcjcm Mark; Jacobs, B.

doi:10.1149/1.1922874

Cited by 5 publications

(6 citation statements)

References 9 publications

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“…However, while iii) "GaN:Mg" samples were used as-grown, iv) "p-GaN:Mg" samples were annealed for 20 min at 800°C under nitrogen atmosphere in order to drive out H and electrically activate the Mg, typically leading to hole concentrations of 1-2×10 17 cm −3 and Hall mobilities of 10-15 cm 2 V −1 s −1 . [40] For the present study, only [0001] (c-axis) patterns were measured, since these allow to quantify with high accuracy the relative amounts of interstitial vs substitutional 27 Mg. The orientation of the samples was thus kept fixed during most of the measurements, except when moving the samples laterally in order to change to new beam spots for measuring the detailed fluence dependence at different temperatures.…”

Section: Resultsmentioning

confidence: 99%

“…We interpret this fact as due to an increase in the concentration of Ga vacancies VGa with Mg fluence, which increases the probability that newly implanted 27 Mg is incorporated on substitutional Ga sites instead of staying in an interstitial position. While no studies on the damage accumulation in GaN for 10 13 -10 14 cm −2 RT implantation of ions with masses similar to 27 Mg are to be found in the literature, it has been reported that following 40 Ar implantation the number of displaced host atoms increases linearly with fluence in this range. [44,45] It is hence plausible to assume that this also applies to the case of VGa defects following Mg implantation.…”

Section: Resultsmentioning

confidence: 99%

“…However, while iii) “GaN:Mg” samples were used as‐grown, iv) “ p ‐GaN:Mg” samples were annealed for 20 min at 800 °C under nitrogen atmosphere in order to drive out H and electrically activate the Mg, typically leading to hole concentrations of 1–2 × 10 17 cm −3 and Hall mobilities of 10–15 cm 2 V −1 s −1 . [ 40 ]…”

Section: Resultsmentioning

confidence: 99%

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Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN

Wahl

Correia

Costa

et al. 2021

Adv Elect Materials

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Despite the renewed interest in ion implantation doping of GaN, efficient electrical activation remains a challenge. The lattice location of 27Mg is investigated in GaN of different doping types as a function of implantation temperature and fluence at CERN's ISOLDE facility. The amphoteric nature of Mg is elucidated, i.e., the concurrent occupation of substitutional Ga and interstitial sites: following room temperature ultra‐low fluence (≈2 × 1010 cm−2) implantation, the interstitial fraction of Mg is highest (20–24%) in GaN pre‐doped with stable Mg during growth, and lowest (2–6%) in n‐GaN:Si, while undoped GaN shows an intermediate interstitial fraction of 10–12%. Both for p‐ and n‐GaN prolonged implantations cause interstitial 27Mg to approach the levels found for undoped GaN. Implanting above 400 °C progressively converts interstitial Mg to substitutional Ga sites due to the onset of Mg interstitial migration (estimated activation energy 1.5–2.3 eV) and combination with Ga vacancies. In all sample types, implantations above a fluence of 1014 cm−2 result in >95% substitutional Mg. Ion implantation is hence a very efficient method to introduce Mg into substitutional Ga sites, i.e., challenges toward high electrical activation of implanted Mg are not related to lack of substitutional incorporation.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN

Wahl

Correia

Costa

et al. 2021

Adv Elect Materials

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“…However, while "GaN:Mg" samples were used as-grown, "p-GaN:Mg" samples were annealed for 20 min at 800°C under nitrogen atmosphere in order to drive out H and electrically activate the Mg [24]. While no electrical characterization was performed for the p-GaN:Mg used in this experiment, typical hole concentrations and Hall mobilities for samples produced using the same equipment under almost identical conditions are 1-2×10 17 cm −3 and 10-15 cm 2 /Vs [25]. The EC measurements were performed simultaneously with 50 keV implantations into a 1 mm diameter beam spot using the on-line setup described in Ref.…”

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confidence: 99%

Lattice Location of Mg in GaN: A Fresh Look at Doping Limitations

et al. 2017

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Radioactive27 Mg (t 1/2 =9.5 min) was implanted into GaN of different doping types at CERN's ISOLDE facility and its lattice site determined via β − emission channeling. Following implantations between room temperature and 800°C, the majority of 27 Mg occupies the substitutional Ga sites, however, below 350°C significant fractions were also found on interstitial positions ~0.6 Å from ideal octahedral sites. The interstitial fraction of Mg was correlated with the GaN doping character, being highest (up to 31%) in samples doped p-type with 2×1019 cm −3 stable Mg during epilayer growth, and lowest in Si-doped n-GaN, thus giving direct evidence for the amphoteric character of Mg. Implanting above 350°C converts interstitial 27 Mg to substitutional Ga sites, which allows estimating the activation energy for migration of interstitial Mg as between 1.3 and 2.0 eV.

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“…Three of the samples were epilayers grown at the University of Cambridge: a not intentionally doped GaN (nid-GaN #1), an n-GaN:Si layer doped with 1×10 19 cm −3 Si, and a p-GaN:Mg layer doped during growth with 2×10 19 cm −3 Mg and annealed for 20 min at 800°C under nitrogen atmosphere in order to drive out H and electrically activate the Mg (typical hole concentrations 1-2×10 17 cm −3 and Hall mobilities 10-15 cm 2 /Vs [42]). In addition, two undoped layers (nid-GaN #2 and #3) from other suppliers were used during exploratory measurements.…”

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confidence: 99%

Direct evidence of Be as an amphoteric dopant in GaN

et al. 2022

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The interest in Be as an impurity in GaN stems from the challenge to understand why GaN can be doped ptype with Mg, while this does not work for Be. While theory has actually predicted an acceptor level for Be that is shallower than Mg, it was also argued that Be is not a suitable acceptor because its amphoteric nature, i.e. its tendency to occupy substitutional Ga as well as interstitial sites, would be considerably more pronounced than for Mg and hence lead to self-compensation. Using the emission channeling technique at the ISOLDE/CERN facility, we determined the lattice location of 11 Be (t1/2=13.8 s) in different doping types of GaN as a function of implantation temperature. We find within an accuracy of 0.08 Å that the location of interstitial Be is the one predicted by theory. The room temperature interstitial fraction of 11 Be was correlated with the GaN doping type, being highest (up to ~80%) in p-type and lowest in n-GaN, thus giving direct evidence for the amphoteric character of Be. We find that interstitial 11 Be fractions are generally much higher than for Mg, which confirms that indeed self-compensation should be considerably more pronounced for Be. With rising implantation temperature, an increasing conversion of interstitial to substitutional Be is observed, involving at least two clearly identifiable steps at 50-150 °C and 350-500 °C. This suggests that the migration of interstitial Be may be subject to two different activation energies.

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Enhancement of p-GaN Conductivity Using PECVD SiO[sub x]

Cited by 5 publications

References 9 publications

Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN

Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN

Lattice Location of Mg in GaN: A Fresh Look at Doping Limitations

Direct evidence of Be as an amphoteric dopant in GaN

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